The scans with the ADF were at 600 dpi and both "auto selecting" and selecting the actual paper size gives the same results.
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Other things that will conceiveably screw up the machine. You get options of Abort and Logoff; or the option Cancel is visible, but "the operation cannot be cancelled" when you touch Cancel or it just won't work and timeout.
Not scanning in 600 dpi when scanning to PDF. OCR should automatically select 600 dpi.
You can really confuse it by flipping the dimensions of the Aux paper tray. Put 11 where the 8.5 is and 8,5 where the 11 is.
I didn't play much with this.
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A graduate student finished programming his thesis which was a device driver for a 1980's computer, He said, see if you can crash it. I typed 3 characters on a logged out terminal and took down up to 32 users. I knew it would be a special case. It caused the character position on the screen to go negative.